feat: add SharePanel component for social sharing with QR code support

- Implemented SharePanel component in `SharePanel.astro` for sharing content on social media platforms.
- Integrated QR code generation for WeChat sharing using the `qrcode` library.
- Added localization support for English and Chinese languages.
- Created utility functions in `seo.ts` for building article summaries and FAQs.
- Introduced API routes for serving IndexNow key and generating full LLM catalog and summaries.
- Enhanced SEO capabilities with structured data for articles and pages.

frontend/src/components/seo/PageViewTracker.astro

@@ -0,0 +1,89 @@
+---
+interface Props {
+  pageType: string;
+  entityId?: string;
+  postSlug?: string;
+}
+
+const props = Astro.props;
+const pageType = props.pageType;
+const entityId = props.entityId ?? '';
+const postSlug = props.postSlug ?? '';
+---
+
+<script is:inline define:vars={{ pageType, entityId, postSlug }}>
+  (() => {
+    const endpoint = '/api/analytics/content';
+    const storageKey = `termi:pageview:${pageType}:${entityId || postSlug || 'root'}`;
+
+    function ensureSessionId() {
+      try {
+        const existing = window.sessionStorage.getItem(storageKey);
+        if (existing) return existing;
+        const nextId = crypto.randomUUID();
+        window.sessionStorage.setItem(storageKey, nextId);
+        return nextId;
+      } catch {
+        return `${Date.now()}-${Math.random().toString(36).slice(2)}`;
+      }
+    }
+
+    function getReferrerHost() {
+      try {
+        return document.referrer ? new URL(document.referrer).host : '';
+      } catch {
+        return '';
+      }
+    }
+
+    function normalizeSource(value) {
+      const source = String(value || '').trim().toLowerCase();
+      if (!source) return 'direct';
+      if (source.includes('chatgpt') || source.includes('openai')) return 'chatgpt-search';
+      if (source.includes('perplexity')) return 'perplexity';
+      if (source.includes('copilot') || source.includes('bing')) return 'copilot-bing';
+      if (source.includes('gemini')) return 'gemini';
+      if (source.includes('google')) return 'google';
+      if (source.includes('claude')) return 'claude';
+      if (source.includes('duckduckgo')) return 'duckduckgo';
+      if (source.includes('kagi')) return 'kagi';
+      return source;
+    }
+
+    function buildMetadata() {
+      const currentUrl = new URL(window.location.href);
+      const utmSource = currentUrl.searchParams.get('utm_source')?.trim() || '';
+      const utmMedium = currentUrl.searchParams.get('utm_medium')?.trim() || '';
+      const utmCampaign = currentUrl.searchParams.get('utm_campaign')?.trim() || '';
+      const utmTerm = currentUrl.searchParams.get('utm_term')?.trim() || '';
+      const utmContent = currentUrl.searchParams.get('utm_content')?.trim() || '';
+      const referrerHost = getReferrerHost();
+
+      return {
+        pageType,
+        entityId: entityId || undefined,
+        referrerHost: referrerHost || undefined,
+        utmSource: utmSource || undefined,
+        utmMedium: utmMedium || undefined,
+        utmCampaign: utmCampaign || undefined,
+        utmTerm: utmTerm || undefined,
+        utmContent: utmContent || undefined,
+        landingSource: normalizeSource(utmSource || referrerHost),
+      };
+    }
+
+    fetch(endpoint, {
+      method: 'POST',
+      headers: { 'Content-Type': 'application/json' },
+      keepalive: true,
+      body: JSON.stringify({
+        event_type: 'page_view',
+        path: `${window.location.pathname}${window.location.search}`,
+        post_slug: postSlug || undefined,
+        session_id: ensureSessionId(),
+        referrer: document.referrer || undefined,
+        metadata: buildMetadata(),
+      }),
+    }).catch(() => undefined);
+  })();
+</script>